The present invention relates to a method of reducing the concentration of a liquid resin in an aqueous composition which contains an emulsified liquid resin and at least one ionic compound.
Liquid resins are well known and useful for a wide variety of applications, for example in the coating and paint industries, electrical and structural applications, as well as for producing adhesives. Exemplary of liquid resins, which are manufactured, i.e. synthetic, are liquid epoxy, phenolic and polycarbonate resins, poly(vinyl alcohol), polyacrylamides and poly(acrylic acid) and derivatives.
According to many known processes synthetic liquid resins are produced in an aqueous system. Wastewater from such production processes often contains residual amounts of emulsified liquid resin. Frequently the wastewater also contains one or more types of ionic compounds which are used during the production process or which are produced as a by-product in the production process. Due to the increasing awareness of environmental problems caused by emulsified liquid resins in wastewater streams and due to increasingly stringent environmental regulations much research effort has been spent in reducing the concentration of emulsified liquid resins in aqueous compositions, such as wastewater, originating from a process for producing the liquid resin. Generally, applied methods of treating wastewater are standard flocculation, biodegradation methods etc. However, many liquid resins, such as epoxy resins, are poorly biodegradable.
An abstract of published Japanese patent application JP-A-59156483 suggests the treatment of an effluent containing polymerizable organic matters, such as monomers or oligomers of epoxy resin, polyester or acrylic ester, by selective adsorption on cellulose-type powder. The effluent to be treated is passed through a layer of cellulose-type powder, e.g. saw dust, pulp insoluble in water, paper and waste coconut seed fibers etc. The polymerizable organic matter is adsorbed by the cellulose-type powder and the powder and the organic matters contained therein are removed from the effluent and incinerated. Prior to contacting with the cellulose-type powder, the effluent is preferably heated to accelerate polymerization reaction of the polymerizable organic matters contained in the effluent. However, this method requires the incineration of large amounts of moist cellulose-type material on which the organic matters have been adsorbed.
Accordingly, it would be desirable to find another method of reducing the concentration of a liquid resin in an aqueous composition which contains an emulsified liquid resin and an ionic compound or ionic compounds.
It has now been found that the concentration of a liquid resin in such an aqueous composition can be reduced by contacting the aqueous composition with a solution of a non-ionic cellulose ether in a liquid diluent to produce an agglomerate of cellulose ether and liquid resin. The agglomerate can be removed from the mixture of aqueous composition and cellulose ether solution.